Construction machine, as well as method for milling off and transporting away a milled-off stream of material of a construction machine

ABSTRACT

In a self-propelled construction machine, in particular cold milling machine, recycler or surface miner, for working ground surfaces, comprising a milling drum supported at a machine frame and a conveying device arranged at the machine frame which accepts the milled-off material from the milling drum during the working operation and, on a continuously revolving first transport belt, unloads it, in conveying direction, onto a point of discharge at a discharge end along a parabolic trajectory, it is provided for the following features to be achieved: as a minimum, the last section of the conveying device as seen in conveying direction comprises no less than one continuously revolving cover belt arranged above the transport belt, said cover belt extending essentially parallel to the transport belt and resting against the milled-off material on the transport belt at least in a partial section of the length of the transport belt.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a self-propelled construction machine, inparticular cold milling machine, recycler, surface miner, and to amethod for milling off and transporting away a milled-off stream ofmaterial.

2. Description of the Prior Art

When removing ground or road material using a road milling machine,milled material is produced that is loaded onto a transport vehicle bythe road milling machine by means of a conveying device. In thisarrangement, the conveying device may comprise one or multiple transportbelts which accept the material from the milling drum and unload it at adischarge end along a parabolic discharge trajectory. Loading of themilled material is effected in operation, that is, while the roadmilling machine and the transport vehicle are in motion. In the process,it is of significance to transfer the milled material onto the transportvehicle in a controlled fashion as the milled-off material is otherwisenot unloaded to a specified point of discharge and may impair thetraffic flowing alongside or, if the milled material does not entirelycome down on the loading surface of the transport vehicle, causesadditional sweeping operations.

To guide the stream of material, at least the last section of theconveying device as seen in conveying direction may preferably bemounted to pivot laterally and/or in height, in which case the parabolictrajectory can additionally be influenced by means of the adjustment ofthe conveying speed.

The properties of the milled-off material differ depending on the taskto be performed, for example, fine milling or the removal of completeroad pavements, as well as on the operating parameters adjusted, forexample, the advance speed of the road milling machine, the millingdepth and the type of the milled-off material.

The quantity of the material milled off per unit of time, as well as thecomposition of the same and the size of the fragments of milledmaterial, in particular, may differ.

It is generally known to load the milled-off material onto a transportvehicle by means of one or multiple successive transport belts.

With steep-incline conveyors, it is also known to use a double-belt beltconveyor (EP 0 249 084).

With the simple transport belts known from road milling machines, adiscontinuous stream of material may form as a result of theinhomogeneity of the milled material and the changing quantity of themilled material.

This is due to the fact that, depending on the size of the fragments ofthe milled-off material, a relative movement of the fragments amongthemselves and to the transport belt may result, namely, in particularif there is very much or very little milled-off material on thetransport belt, or in the case of slab-like fragments of the milled-offmaterial.

A fluctuating amount of slip may form between the milled-off materialand the transport belt, namely, in particular in the case of a highspeed of the transport belt. As a consequence, different dischargespeeds of individual components of the milled-off material may occur, inwhich case, in addition, flight paths of the different fragments of themilled-off material deviating from the specified parabolic trajectorymay result. A further consequence is that, in the mean, the effectivedischarge speed is lower than the speed of the transport belt whichresults in a loss of energy.

In addition, a decelerated stream of material is more vulnerable toexterior influences, such as wind loads acting transverse to thetransport belt, as the kinematic energy is reduced in conveyingdirection.

SUMMARY OF THE INVENTION

It is therefore the object of the invention to specify a constructionmachine, as well as a method for milling off and transporting away amilled-off stream of material of a construction machine, in which thedischarge of the milled-off material can be computed in an improvedfashion and adjusted with a higher level of reproducibility.

One embodiment advantageously provides for, as a minimum, the lastsection of the conveying device as seen in conveying direction tocomprise no less than one continuously revolving cover belt arrangedabove the transport belt, said cover belt extending essentially parallelto the transport belt and resting against the milled-off material on thetransport belt at least in a partial section of the length of thetransport belt.

The following advantages may be provided:

By arranging no less than one cover belt above the transport belt, theform and direction as well as bundling of the stream of material can beadjusted more precisely. Altogether, a higher and more homogeneousdischarge speed of the milled-off material as well as a more preciseadjustment of the discharge speed can be achieved, especially since animproved transmission of force from the transport belt to the milled-offmaterial can be effected in the sense of a lower amount of slipoccurring.

Lateral sealings, which were needed up to now and generated frictionlosses at the transport belt, are avoided as the sealing is now ensuredby the overlying cover belt. Overall, an improved energy performanceensues, it being possible to reduce the fuel consumption and to bettercomply with legal requirements also in terms of pollutant emission.

In a preferred embodiment, it is intended for the conveying device orthe last section of the conveying device to be arranged to pivot at themachine frame in terms of inclination and/or lateral alignment.

The cover belt is preferably pre-tensionable resiliently in thedirection towards the transport belt. In this arrangement, the contactforce may also be generated by the own weight of the cover belt.

In a preferred embodiment, it is intended for the cover belt to beadjustable in height and/or to be supported in a pre-tensionable fashionin the direction towards the transport belt. Being supported resilientlyenables a part of the weight of the cover belt to be compensated for, orthe initial tension vis-à-vis the weight load to even be increased, oralso just the lower strand to be pressed against the milled-off materialon the transport belt dynamically.

In a further development of the invention, it is intended for thetransport belt to be of foldable design, with a front section of thetransport belt, or a last section as seen in conveying direction, beingpivotable downwards when in a transport position. For this purpose, thecover belt may preferably be of a divided design so that a total of twocover belts arranged behind one another are arranged above the transportbelt. In this arrangement, the last cover belt as seen in the directionof transport is foldable preferably downwards together with the frontsection of the transport belt. The transport length of a road millingmachine can thus be reduced significantly.

The cover belt may also be arranged in the area of the foldable frontsection of the transport belt only.

In a preferred embodiment, it is intended for the transport belt tocomprise support rollers for the upper and lower strands, and for thesupport rollers for the upper strand of the transport belt, in a planeextending orthogonal to the conveying direction, to form a transportchannel with a concave cross-section on the upper strand of thetransport belt.

According to a further development, it is intended for the cover belt tocomprise support rollers for the upper and lower strands of the coverbelt, and for the support rollers for the lower strand of the coverbelt, in a plane extending orthogonal to the conveying direction, toallow flexible adjustment of the cross-sectional shape of the lowerstrand of the cover belt to the quantity of milled material present onthe transport belt. Flexible adjustment of the cross-sectional shape ofthe lower strand to the quantity of milled material present on thetransport belt is effected dynamically at each position of arrangementof the support rollers.

It is preferably intended for articulated support rollers of the lowerstrand of the cover belt to be pre-tensionable resiliently in thedirection towards the first transport belt. To this effect, as aminimum, the support rollers for the upper strand of the transport beltand the support rollers for the lower strand of the cover belt maycomprise multiple roller segments coupled to one another in anarticulated fashion. In this arrangement, the segments of the upperstrand of the transport belt are preferably supported in a fixedposition while the support rollers for the lower strand of the coverbelt are supported in a movable fashion so that the individual rollersegments can assume different angular positions relative to one another.

Alternatively, it is also possible for the support rollers for the lowerstrand of the cover belt to be provided in a V-shaped dual arrangementbehind one another as seen in conveying direction.

The conveying speed of the belts, namely of the transport belt and noless than one cover belt, may be variable and/or adjustableindividually.

The no less than one cover belt may, in the area of the discharge end infront of the end of the transport belt, diverge from the same.

The no less than one cover belt may, in the area of the discharge end,protrude beyond the end of the transport belt as seen in conveyingdirection.

In one embodiment, it may be intended for the cover belt, at thedischarge end, to project vis-à-vis the transport belt as seen in thedirection of transport and for the projecting part of the cover belt tobe pivotable, relative to the transport belt, about an axis extendingtransverse and parallel to the transport belt or to be guided about theend of the transport belt in the shape of an arc. The pivotability ofthe projecting part of the cover belt makes it possible to influence theparabolic discharge trajectory of the milled-off stream of material.

In such an embodiment in which, for example, the lower strand of thecover belt is guided about the end of the transport belt in the shape ofan arc, there is the possibility for the last deflection roller of thecover belt to be moved from a position in which the lower strand of thecover belt surrounds the end of the transport belt in the shape of anarc, for example, in an angular range of approx. 90°, into a position inwhich the last deflection roller as seen in the direction of transportis located in a rectilinear extension of the cover belt.

Depending on the position of said deflection roller, the parabolictrajectory can be changed so as to enable adjustment of the point ofimpingement of the milled-off material on a loading surface of atransport vehicle.

It may be intended for the belts to comprise an essentially rectilineardeflection roller each on the inlet side and outlet side, and for noless than one of the last deflection rollers as seen in conveyingdirection to be pivotable relative to the respective opposite deflectionroller. The adjustability of the deflection rollers at the discharge endenables the stream of material to be bundled more strongly, should theneed arise, and the parabolic trajectory to be shortened, whereappropriate, despite a high conveying speed so that the point ofdischarge is moved closer to the conveying device.

In a method for milling off and transporting away a milled-off stream ofmaterial of a road milling machine, it is intended for the milled-offmaterial to be transported, at least on a part of the length of thetransport belt, between a transport belt and no less than one uppercover belt of the conveying device.

In the process, the cover belt may be pre-tensioned resiliently in thedirection towards the lower transport belt carrying the milled-offmaterial at least in that part which is in contact with the milled-offmaterial.

The milled-off material may be transported in a transport channel of thelower transport belt, in which process the lower strand of the uppercover belt is guided in such a fashion that the strand, which has aconvex to concave cross-sectional shape depending on the quantity of themilled-off material, is pressed against the milled-off material.

The belts accepting the milled-off material between themselves may beguided in a converging fashion on the inlet side and/or in a divergingfashion on the outlet side.

In the following, embodiments of the invention are explained in moredetail with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following is shown:

FIG. 1 a road milling machine,

FIG. 2 a section through the conveying device according to FIG. 1 in alongitudinal median plane,

FIG. 3 a section along line III-III in FIG. 2,

FIG. 4 a section according to FIG. 3 with loaded transport belt,

FIG. 5 a side view of the conveying device in folded state,

FIG. 6 an alternative design of the support rollers for the upper strandof the transport belt, and

FIG. 7 an embodiment with a projecting and pivotable cover belt.

DETAILED DESCRIPTION

FIG. 1 shows a construction machine 1 for milling ground surfaces ortraffic surfaces which is also referred to as a cold milling machine.

The cold milling machine features a chassis comprising, for example,four crawler track units, said chassis supporting the machine frame 2 ofthe road milling machine 1. It is understood that the crawler trackunits may be substituted, wholly or in part, by wheels.

A milling drum 6 extending transversely to the direction of travel ismounted in the machine frame 2. The milling depth is preferably set bymeans of the height adjustment of the crawler track units via liftingcolumns. The cold milling machine depicted in FIG. 1 is also referred toas a front-loading road milling machine as it is capable of conveyingthe milled-off material 3 towards the front as seen in the direction oftravel onto a point of discharge on a transport vehicle. A firsttransport belt 5 of a conveying device 18 is arranged in front of themilling drum 6 as seen in the direction of travel, said first transportbelt 5 preferably transferring the milled-off material 3 to a secondtransport belt 10. It is understood that the road milling machine 1 mayalso comprise a single transport belt only which may also be arranged atthe rear of the road milling machine 1.

The cold milling machine depicted in FIG. 1 shows a typical embodimentof a construction machine which also allows the use of a foldingconveying device 18. A foldable transport belt is generally alreadyknown from EP 2 113 613 A1. (U.S. Pat. No. 8,424,666)

FIG. 2 shows a partial section through the longitudinal median plane ofthe conveying device 18 which comprises a lower transport belt 10 andtwo successive upper cover belts 12 a, 12 b. No less than one cover belt12 a, 12 b is arranged above the transport belt 10 of the conveyingdevice 18 so that, notwithstanding the embodiments shown in the figures,a single cover belt 12 only may also be arranged above the transportbelt 10.

The transport and cover belts 10, 12 a, 12 b are continuously revolvingbelts which revolve about essentially rectilinear deflection rollers 20to 25, where the front deflection rollers 20, 22, 24 as seen inconveying direction 30 may preferably be driven deflection rollers, andwhere the rear deflection rollers 21, 23, 25 as seen in conveyingdirection 30 may also be of spherical design.

The belts 10, 12 a, 12 b each comprise an upper strand 13, 15 and alower strand 14, 16, in which arrangement the lower strand 14 of thesingle cover belt or the cover belts 12 a, 12 b may be pre-tensioned inthe direction towards the upper strand 15 of the transport belt 10.

Altogether, the no less than one cover belt 12 a, 12 b may be adjustablein height relative to the transport belt 10. To this effect, theconveying device 18 comprises a frame 44 for the transport belt 10 andframes 42 a, 42 b for the cover belts 12 a, 12 b, with guiding elements40 being intended at the sides of said frames which enable the no lessthan one cover belt 12 a, 12 b to be adjusted in height relative to thetransport belt 10.

In this arrangement, the cover belts 12 a, 12 b, with their lowerstrands 14 each, may rest, due to their own weight, on the transportbelt 10 or on the milled-off material 3 transported on the transportbelt 10.

The lateral guiding devices 40 (FIG. 1 and FIG. 5), which are arrangedon both sides of the cover and transport belts 10, 12 a, 12 b, may becombined with spring devices so that the cover belts 12 a, 12 b do notrest on the upper strand 15 of the transport belt 10 with their fullweight.

It goes without saying that the guiding devices 40 may also be adjustedso as to enable a specific permanent distance to be preset between theframes 42 a, 42 b, 44 of the transport and cover belts 10, 12 a 12 b.

The guiding elements 40 may alternatively also be combined with springelements which pre-tension the frame 42 a, 42 b of the no less than onecover belt 12 a, 12 b downwards. As can best be inferred from FIGS. 3and 4, which represent a section along line III-III in FIG. 2, supportrollers 32 are preferably intended for the upper strand 15 of thetransport belt 10, with the roller segments 32 a, 32 b, 32 c of saidsupport rollers 32 being connected to one another in an articulatedfashion and, together with the upper strand 15, creating a bed ofconcave cross-section for the milled-off material 3. In this design, thesupport rollers 32 are preferably arranged in a fixed position in theframe 44.

The lower strand 14 of the no less than one cover belt 12 a, 12 bcomprises movable support rollers 34 which may also be segmented and areconnected to one another in an articulated fashion such that they canchange from a lowest position with minimal loading of the transport belt10, as shown in FIG. 3, to a position in loaded state of the transportbelt 10, as shown in FIG. 4. A gear, for example, is intended to thiseffect which guides the support rollers 34 in an essentially orthogonalplane to the cover belt 12 a and 12 b respectively. In this arrangement,each support roller 34 is comprised of, for example, three rollersegments 34 a, 34 b, 34 c, with all roller segments being guided in theorthogonal plane by, for example, a four-link mechanism 50 at the frame42 a, 42 b.

The support rollers 34 for the lower strand 14 of the cover belt 12 a or12 b respectively may be pre-tensioned against the lower strand 14 bymeans of spring elements, for example, Rosta-Blocks.

The upper support rollers 35 of the no less than one cover belt 12 a, 12b and the lower support rollers 33 of the transport belt 10 may berectilinear rollers which are supported in a fixed position relative tothe frames 42 a, 42 b, 44.

Furthermore, the transport or cover belts 10, 12 a, 12 b, respectivelymay comprise lateral guiding devices 46 which are arranged at the upperstrand 13 of the no less than one cover belt and at the lower strand 16of the transport belt respectively in a specific height positionrelative to the frames 42 a, 42 b, 44 in order to ensure a lateralguidance. The cover belts 12 a, 12 b are guided, on the inlet side,between the deflection rollers 23, 25 and the first support roller 34 ina converging fashion to the transport belt 10 while, on the outlet side,they are guided in a diverging fashion in the direction towards thefront deflection rollers 22, 24 as seen in conveying direction 30.

In this design, the front deflection roller 22 as seen in conveyingdirection 30 of the last cover belt 12 b as seen in conveying direction30 may be arranged to pivot relative to the deflection roller 20 of thetransport belt 10 so that the direction of discharge of the milled-offmaterial 3 between the transport belt 10 and the no less than one lastcover belt 12 b can be adjusted in different ways. Alternatively thedeflection roller 20 of the transport belt or both deflection rollers20, 22 can be pivotable.

The upper strand 15 of the transport belt 10 and the lower strand 14 ofthe no less than one cover belt 12 a, 12 b, respectively move, inconveying direction 30, with the same, preferably adjustable conveyingspeed or with an adjustable different conveying speed. The shape of theparabolic trajectory 9 at the discharge end 11 can be influenced bymeans of the conveying speed and the height adjustment of the conveyingdevice 18, as well as by means of the adjustment of the distance or thepivoting angle, respectively between the last cover belt 12 b and thetransport belt 10.

As can be inferred from FIG. 5, the front section of the conveyingdevice 18 can be folded downwards and locked, for transport purposes, inan end position inferable from FIG. 5. An example of a swivel gear 60suitable for this purpose has, in principle, been described in EP 2 113613 A (U.S. Pat. No. 8,424,666). It is preferably intended for thefolded front section of the conveying device 18 to have its own coverbelt 12 b. Such segmentation of the cover belt 12 a, 12 b arranged abovethe transport belt 10 enables the folding possibility of the transportbelt 10 to be maintained.

FIG. 6 shows an alternative embodiment for the support rollers 32 of theupper strand 15 of the transport belt 10.

In this embodiment, a dual arrangement of rectilinear support rollers 32is used which are arranged immediately behind one another in conveyingdirection 30 and together enable a V-shaped support, in conveyingdirection 30, of the upper strand 15 of the transport belt 10.

The transport and cover belts 10, 12 a, 12 b feature a profile on thesurfaces facing the milled-off material 3 which minimize the amount ofslip on the transport surface.

FIG. 7 shows an embodiment in which a projecting section 12 c of thecover belt 12 b is pivotable in order to adjust the parabolic trajectoryof the milled-off stream of material 3 to a specified point of discharge27.

The upper cover belt 12 b is extended, at the discharge end 11, beyondthe deflection roller 22 and comprises, at a distance from thedeflection roller 22, an additional deflection roller 26 which, in thedirection towards the transport belt 10, is pivotable about a normallyhorizontal axis 36 preferably coaxially to the axis of the deflectionroller 22.

It is understood that, notwithstanding the illustration in FIG. 7, thesection 12 c projecting vis-à-vis the transport belt 10 may also belonger in such a fashion that the lower strand 14 of the cover belt 12b, 12 c can wrap around the transport belt 10, in the area of thedeflection roller 20, for example, in the shape of an arc of up to 90°.

As depicted in FIG. 7 in dashed lines, the deflection roller 26 may alsobe brought into a position in which the pivotable section 12 c of thecover belt 12 b extends in a rectilinear elongation of the remainingcover belt 12 b. In this case, a different parabolic trajectory resultsfor the milled-off material 3 that is depicted in dashed lines in FIG.7.

It is thus possible, by means of the pivoting position of the projectingsection 12 c, to determine the position of the point of discharge 27 ona loading surface 28 of a transport vehicle.

What is claimed is:
 1. A cold milling machine for working groundsurfaces, comprising: a machine frame; a milling drum supported from themachine frame; a plurality of wheels or tracks supporting the machineframe from the ground surface so that the cold milling machine is aself-propelled mobile cold milling machine having a direction of travelduring working operation; a conveyor system arranged to acceptmilled-off material from the milling drum during working operation, andto unload the milled-off material in a conveying direction from adischarge end of the conveyor system along a parabolic trajectory onto adischarge point, the conveyor system including: at least onecontinuously revolving transport belt having a length and having atransport belt discharge end, the at least one continuously revolvingtransport belt including a transport belt frame; and at least onecontinuously revolving cover belt arranged above at least a last sectionof the transport belt in the conveying direction adjacent the transportbelt discharge end, the cover belt extending essentially parallel to thelength of the transport belt, the cover belt being configured to restagainst milled-off material carried by the transport belt in at least aportion of the length of the transport belt to aid in controlling theparabolic trajectory of the milled-off material to the discharge pointduring working operation of the self-propelled mobile cold millingmachine, the at least one continuously revolving cover belt including acover belt frame, the cover belt frame being adjustable in heightrelative to the transport belt frame; wherein at least a portion of theconveyor system is arranged to pivot relative to the machine frame suchthat both an inclination of the conveyor system and a lateral alignmentof the conveyor system relative to the machine frame are adjustable. 2.The cold milling machine of claim 1, wherein: the cover belt ispre-tensioned toward the transport belt.
 3. The cold milling machine ofclaim 1, wherein: the at least one continuously revolving cover beltcomprises two successive cover belts arranged above the transport belt.4. The cold milling machine of claim 1, wherein: the transport belt isfoldable, and the transport belt includes the last section and anothersection, the last section being pivotable downwards relative to theother section to a transport position; and the cover belt covers atleast the last section of the transport belt.
 5. The cold millingmachine of claim 1, wherein: the transport belt includes an upper strandand a lower strand, and support rollers for the upper strand, thesupport rollers supporting the upper strand such as to form a transportchannel having a concave cross-section on the upper strand of thetransport belt.
 6. The cold milling machine of claim 5, wherein: thesupport rollers for the upper strand of the transport belt each comprisemultiple roller segments coupled to one another in an articulatedfashion.
 7. The cold milling machine of claim 1, wherein: the at leastone cover belt includes an upper strand and a lower strand, and supportrollers for the lower strand, the support rollers allowing a flexibleadjustment of a cross-sectional shape of the lower strand of the coverbelt so that the lower strand contacts a quantity of milled-off materialpresent on the transport belt.
 8. The cold milling machine of claim 7,wherein: the support rollers for the lower strand of the cover belt havean articulated connection to a side frame of the conveyor system, andthe support rollers are resiliently pre-tensioned toward the transportbelt.
 9. The cold milling machine of claim 7, wherein: the supportrollers for the lower strand of the cover belt each comprise multipleroller segments coupled to one another in an articulated fashion. 10.The cold milling machine of claim 1, wherein: the cover belt has aninlet end and an outlet end; the outlet end of the cover belt divergesfrom the transport belt in a conveying direction; and the inlet end ofthe cover belt converges toward the transport belt in the conveyingdirection.
 11. The cold milling machine of claim 1, wherein: thetransport belt includes a last transport belt deflection roller in theconveying direction; the at least one cover belt includes a last coverbelt deflection roller in the conveying direction; and one of the lasttransport belt deflection roller and the last cover belt deflectionroller is pivotable relative to the other.
 12. A method of operating aself-propelled cold milling machine including a milling drum, the methodcomprising: (a) milling off material from a ground surface with themilling drum as the cold milling machine moves across the groundsurface; (b) accepting milled-off material from the milling drum on aconveyor as the cold milling machine moves across the ground surface;(c) transporting the milled-off material between a lower transport beltand an upper cover belt of the conveyor along at least a part of alength of the lower transport belt to a discharge end of the conveyor asthe cold milling machine moves across the ground surface; (d)discharging the milled-off material from the discharge end of theconveyor along a parabolic trajectory to a point of discharge as thecold milling machine moves across the ground surface; (e) pivoting theconveyor relative to the machine frame such that both an inclination ofthe conveyor and a lateral alignment of the conveyor relative to themachine frame are adjusted; and (f) adjusting a height of a cover beltframe of the upper cover belt relative to a transport belt frame of thelower transport belt.
 13. The method of claim 12, further comprising:resiliently pre-tensioning at least a part of the cover belt towards thetransport belt such that the cover belt contacts the milled-off materialon the transport belt along at least part of the transport belt.
 14. Themethod of claim 12, further comprising: folding a front section of theconveyor to a transport position and locking the front section of theconveyor in the transport position.
 15. The method of claim 12, wherein:in step (c), the lower transport belt defines a transport channelcarrying the milled-off material, and a lower strand of the upper coverbelt is pressed against the milled-off material on the lower transportbelt so that a cross-sectional shape of the lower strand of the uppercover belt varies from a convex to a concave shape depending on aquantity of milled-off material carried on the lower transport belt.